1. Field of the Invention
The present general inventive concept relates to an image forming apparatus and a control method to improve image quality, and more particularly to an image forming apparatus which improves color image quality by sharpening color edges and black edges independently, and a control method to improve the image quality.
2. Description of the Related Art
Image processing apparatuses, such as printers, copy machines, facsimile machines, or multifunction devices, print a desired image on paper. In particular, image forming apparatuses, such as copy machines, or multifunction devices, scan documents, generate digital data, convert the digital data into printable data, and print the printable data onto paper.
When an image is scanned and printed, edge pixels of the image are blurred. In order to reduce blurring, the image forming apparatus sharpens the scanned image data.
However, a conventional image forming apparatus sharpens color pixels and black pixels in the same manner. If a sharpened image is printed, under-sharpening occurs at the edges of white areas such as a background, and over-sharpening occurs at the edges of dark areas.
FIG. 1 is a graph illustrating under-sharpening and over-sharpening occurring in the conventional image forming apparatus. In FIG. 1, the dotted line indicates an ideal result after sharpening. Under-sharpening point A indicates that sharpening is not sufficiently performed, and exemplifies a white background area that is not sharpened as white color. Over-sharpening point B indicates that sharpening is over-performed, and exemplifies dark edge areas that are sharpened darker than an actual color. Thus, when a scanned document is printed, image distortion such as noise or artifact images is caused at edges where over-sharpening B or under-sharpening A occurs.